Racial disparities and utilization trends of first-line targeted therapies for metastatic breast cancer

PURPOSE: We aimed to determine temporal trends and racial disparities in utilization and time to treatment initiation (TTI) of CDK4/6 inhibitors (CDK4/6i) and pertuzumab for first-line metastatic breast cancer (MBC). DESIGN: We extracted data from a nationwide electronic health record-derived deidentified database. Female patients ≥18 years old with ER+/HER2- or HER2+ MBC eligible for CDK4/6i(3/2015-10/2021) or pertuzumab(07/2012-09/2021) were included. Our outcomes were adjusted temporal trends in the proportion of patients receiving respective therapies using logistic regression with natural cubic splines for time trends and tested for changes in utilization over time within and between racial groups (non-Hispanic White (NHW) or non-Hispanic Black (NHB). Similar models using linear regression estimated mean TTI. RESULTS: 5173(NHW = 4478; NHB = 695) ER+/HER2- and 2321(NHW = 1915; NHB = 406) HER2+ MBC patients were included. There were significant differences in the proportion initiating CDK4/6i over time within racial groups (NHW, 23.5%(95%CI: 20.1%-27.3%) in 2015 to 53.8%(95%CI: 48.6%-59.0%) in 2021; NHB, 20.6%(95%CI: 11.9%-33.0%) in 2015 to 73.6%(95%CI: 61.7%-83.0%) in 2021) and between groups(p = 0.009). There was a significant increase in utilization of pertuzumab within both racial groups over time(p < 0.001), but no significant difference between groups(p = 0.45). TTI decreased over time with no significant differences in TTI trends between the two groups. CONCLUSIONS: Utilization of targeted therapies increased over time, however NHB patients were less likely to receive CDK4/6i compared to NHW. Approximately half of eligible patients did not receive pertuzumab. Further research is needed to understand mediators and design interventions to address underutilization of these therapies and those contributing to racial disparities in CDK4/6i utilization.